Question

A force acts on a 20kg mass change its velocity from 15m/s to 7m/sec .
Calculate the work done by the force . ​

Answer 1

Answer:

work done is equal to change in energy ie 1/2mv^2

which implies w=1/2m(15^2-7^2)

w=1/2*20*176

w=1760 j

Explanation:

Answer 2

Given:-

• Mass = m = 20kg
• Initial velocity = u = 15m/s
• Final velocity = v = 7m/s

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Need to find:-

• Work done by force =?

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Need to know:-

Work Energy Theorem:-

• This theorem states that the net work done by all the forces on a body is equal the change in its kinetic energy.

• Its given by ΔK.E.

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Work done = ΔK.E

→ Work done

$= \dfrac{1}{2} m {v}^{2} - \dfrac{1}{2} m {u}^{2}$

$\implies = \dfrac{1}{2} m( {v}^{2} - {u}^{2})$

Substitute the values:

$= \dfrac{1}{2} \times 20 \times ( {7}^{2} - {15}^{2} )$

$\implies W = 10 \times (49 - 225)J$

$\implies W = 10 \times(- 176)J$

$\red{\boxed{\bold{\large{\implies W = - 1760Joules}}}}$

The work done by the force is 1760 Joules in the direction opposite to the direction of motion.